Interpreter >> primitiveNextPut: limit := self fetchInteger: StreamReadLimitIndex ofObject: stream. atIx := (array bitAnd: AtCacheMask) + AtPutBase. (index < limit and: [(atCache at: atIx+AtCacheOop) = array])
so basically, it needs ReadLimit to be > 0. (Which is only true for (Read)WriteStreams if created with on:from:to:).
Changing the first line to limit := self fetchInteger: StreamWriteLimitIndex ofObject: stream.
and the primitive now works. ws := WriteStream on: (String new: 500000). [1 to: 500000 do: [:ix | ws nextPut: $a]] timeToRun
before: 130 after: 33
Inserted a counter after the prim call, for the loop above it was always >= 500000, with fix it's >=1.
Cheers, Henry
I opened a Mantis bug report for this issue:
http://bugs.squeak.org/view.php?id=7421
Dave
On Thu, Nov 26, 2009 at 03:10:52PM +0100, Henrik Johansen wrote:
Interpreter >> primitiveNextPut: limit := self fetchInteger: StreamReadLimitIndex ofObject: stream. atIx := (array bitAnd: AtCacheMask) + AtPutBase. (index < limit and: [(atCache at: atIx+AtCacheOop) = array])
so basically, it needs ReadLimit to be > 0. (Which is only true for (Read)WriteStreams if created with on:from:to:).
Changing the first line to limit := self fetchInteger: StreamWriteLimitIndex ofObject: stream.
and the primitive now works. ws := WriteStream on: (String new: 500000). [1 to: 500000 do: [:ix | ws nextPut: $a]] timeToRun
before: 130 after: 33
Inserted a counter after the prim call, for the loop above it was always >= 500000, with fix it's >=1.
Cheers, Henry
On Thu, Nov 26, 2009 at 8:43 AM, David T. Lewis lewis@mail.msen.com wrote:
I opened a Mantis bug report for this issue:
http://bugs.squeak.org/view.php?id=7421
Dave
I wouldn't bother trying to fix the primitive. Both in VisualWorks and at Teleplace the experience has been the same, getting rid of the primitives for next, nextPut: and atEnd sped things up. The system is simply too complex nowadays for these primitives to pay for themselves because they only cover a small number of cases. The primitives support Array and ByteString bow there are so many different kinds of arrays being streamed over that the cost of primitive failures outweigh the benefits of primitive successes.
On Thu, Nov 26, 2009 at 03:10:52PM +0100, Henrik Johansen wrote:
Interpreter >> primitiveNextPut: limit := self fetchInteger: StreamReadLimitIndex ofObject: stream. atIx := (array bitAnd: AtCacheMask) + AtPutBase. (index < limit and: [(atCache at: atIx+AtCacheOop) = array])
so basically, it needs ReadLimit to be > 0. (Which is only true for
(Read)WriteStreams if created with on:from:to:).
Changing the first line to limit := self fetchInteger: StreamWriteLimitIndex ofObject: stream.
and the primitive now works. ws := WriteStream on: (String new: 500000). [1 to: 500000 do: [:ix | ws nextPut: $a]] timeToRun
before: 130 after: 33
Inserted a counter after the prim call, for the loop above it was always = 500000, with fix it's >=1.
Cheers, Henry
On Thu, 26 Nov 2009, Eliot Miranda wrote:
I wouldn't bother trying to fix the primitive. Both in VisualWorks and at Teleplace the experience has been the same, getting rid of the primitives for next, nextPut: and atEnd sped things up. The system is simply too complex nowadays for these primitives to pay for themselves because they only cover a small number of cases. The primitives support Array and ByteString bow there are so many different kinds of arrays being streamed over that the cost of primitive failures outweigh the benefits of primitive successes.
We are using these primitives in our own stream implementation like this:
next
<primitive: 65> [ position < readLimit ] whileFalse: [ self receiveData ]. ^buffer at: (position := position + 1)
And it does make a difference (buffer is a 8kiB sized ByteArray). Would this be faster without the primitive?
Levente
Hi Levente,
On Thu, Nov 26, 2009 at 12:01 PM, Levente Uzonyi leves@elte.hu wrote:
On Thu, 26 Nov 2009, Eliot Miranda wrote:
I wouldn't bother trying to fix the primitive. Both in VisualWorks and at Teleplace the experience has been the same, getting rid of the primitives for next, nextPut: and atEnd sped things up. The system is simply too complex nowadays for these primitives to pay for themselves because they only cover a small number of cases. The primitives support Array and ByteString bow there are so many different kinds of arrays being streamed over that the cost of primitive failures outweigh the benefits of primitive successes.
We are using these primitives in our own stream implementation like this:
next
<primitive: 65> [ position < readLimit ] whileFalse: [ self receiveData ]. ^buffer at: (position := position + 1)And it does make a difference (buffer is a 8kiB sized ByteArray). Would this be faster without the primitive?
I can't guarantee it. You'd have to measure. All I can say is that we found it better to get rid of the stream primitives in VisualWorks and in the Cog JIT. Looking at the Squeak VM code I think the primitives will still win in the interpreter; after all they use the same machinery as at: and at:put:. But in a JIT they'll likely loose.
Since the Cog JIT isn't available yet I'm not really being helpful. I should think before I blurt. Apologies.
Eliot
Levente
On 26.11.2009 23:26, Eliot Miranda wrote:
Hi Levente,
On Thu, Nov 26, 2009 at 12:01 PM, Levente Uzonyi <leves@elte.hu mailto:leves@elte.hu> wrote:
On Thu, 26 Nov 2009, Eliot Miranda wrote: I wouldn't bother trying to fix the primitive. Both in VisualWorks and at Teleplace the experience has been the same, getting rid of the primitives for next, nextPut: and atEnd sped things up. The system is simply too complex nowadays for these primitives to pay for themselves because they only cover a small number of cases. The primitives support Array and ByteString bow there are so many different kinds of arrays being streamed over that the cost of primitive failures outweigh the benefits of primitive successes. We are using these primitives in our own stream implementation like this: next <primitive: 65> [ position < readLimit ] whileFalse: [ self receiveData ]. ^buffer at: (position := position + 1) And it does make a difference (buffer is a 8kiB sized ByteArray). Would this be faster without the primitive?I can't guarantee it. You'd have to measure. All I can say is that we found it better to get rid of the stream primitives in VisualWorks and in the Cog JIT. Looking at the Squeak VM code I think the primitives will still win in the interpreter; after all they use the same machinery as at: and at:put:. But in a JIT they'll likely loose.
Since the Cog JIT isn't available yet I'm not really being helpful. I should think before I blurt. Apologies.
Eliot
Levente
FWIW, I'd take a JIT anyday over this bug getting fixed :) On the other hand, it's a one-word fix which merely improves performace while we're waiting (unless someone decides to remove the primtive calls from the image altogether, then it merely becomes obsolete), so I hardly see the harm in applying it.
Cheers, Henry
PS. Speaking of unneccessary overhead, what about that collection class == ByteString part for _every_ stream nextPut: , when ByteString at:put: will handle the case correctly anyways if collection is in fact a ByteString? Not to mention how it performs for ByteString currencly, seeing as the primitive now _does_ fail every time.
2009/11/27 Eliot Miranda eliot.miranda@gmail.com:
Hi Levente,
On Thu, Nov 26, 2009 at 12:01 PM, Levente Uzonyi leves@elte.hu wrote:
On Thu, 26 Nov 2009, Eliot Miranda wrote:
I wouldn't bother trying to fix the primitive. Both in VisualWorks and at Teleplace the experience has been the same, getting rid of the primitives for next, nextPut: and atEnd sped things up. The system is simply too complex nowadays for these primitives to pay for themselves because they only cover a small number of cases. The primitives support Array and ByteString bow there are so many different kinds of arrays being streamed over that the cost of primitive failures outweigh the benefits of primitive successes.
We are using these primitives in our own stream implementation like this:
next
<primitive: 65> [ position < readLimit ] whileFalse: [ self receiveData ]. ^buffer at: (position := position + 1)
And it does make a difference (buffer is a 8kiB sized ByteArray). Would this be faster without the primitive?
I can't guarantee it. You'd have to measure. All I can say is that we found it better to get rid of the stream primitives in VisualWorks and in the Cog JIT. Looking at the Squeak VM code I think the primitives will still win in the interpreter; after all they use the same machinery as at: and at:put:. But in a JIT they'll likely loose. Since the Cog JIT isn't available yet I'm not really being helpful. I should think before I blurt. Apologies.
Apologies accepted. ;) Nevertheless, i think that reducing the set of VM responsibilities by moving them to image side is a good tendency, because the less classes/formats VM knows about , the less complex it is, and system is more flexible.
Eliot
Levente
On Thu, 26 Nov 2009, Eliot Miranda wrote:
I can't guarantee it. You'd have to measure. All I can say is that we found it better to get rid of the stream primitives in VisualWorks and
in
the Cog JIT. Looking at the Squeak VM code I think the primitives will still win in the interpreter; after all they use the same machinery as
at:
and at:put:. But in a JIT they'll likely loose.
That sounds great.
Since the Cog JIT isn't available yet I'm not really being helpful. I should think before I blurt. Apologies.
No problem, I hope I can measure the difference "real soon now". :)
Levente
Eliot
On Thu, Nov 26, 2009 at 03:10:52PM +0100, Henrik Johansen wrote:
Interpreter >> primitiveNextPut: limit := self fetchInteger: StreamReadLimitIndex ofObject: stream. atIx := (array bitAnd: AtCacheMask) + AtPutBase. (index < limit and: [(atCache at: atIx+AtCacheOop) = array])
so basically, it needs ReadLimit to be > 0. (Which is only true for (Read)WriteStreams if created with on:from:to:).
Changing the first line to limit := self fetchInteger: StreamWriteLimitIndex ofObject: stream.
and the primitive now works. ws := WriteStream on: (String new: 500000). [1 to: 500000 do: [:ix | ws nextPut: $a]] timeToRun
before: 130 after: 33
Inserted a counter after the prim call, for the loop above it was always >= 500000, with fix it's >=1.
Can anyone comment as to whether the above fix is correct? It looks right to me, but it would be good if someone familiar with #primitiveNextPut and the AtCache could review it.
I note that this primitive has not changed since 1998, so this would rate as a really excellent bug catch!
http://bugs.squeak.org/view.php?id=7421
Thanks, Dave
On Fri, Nov 27, 2009 at 9:03 AM, David T. Lewis lewis@mail.msen.com wrote:
On Thu, Nov 26, 2009 at 03:10:52PM +0100, Henrik Johansen wrote:
Interpreter >> primitiveNextPut: limit := self fetchInteger: StreamReadLimitIndex ofObject: stream. atIx := (array bitAnd: AtCacheMask) + AtPutBase. (index < limit and: [(atCache at: atIx+AtCacheOop) = array])
so basically, it needs ReadLimit to be > 0. (Which is only true for
(Read)WriteStreams if created with on:from:to:).
Changing the first line to limit := self fetchInteger: StreamWriteLimitIndex ofObject: stream.
and the primitive now works. ws := WriteStream on: (String new: 500000). [1 to: 500000 do: [:ix | ws nextPut: $a]] timeToRun
before: 130 after: 33
Inserted a counter after the prim call, for the loop above it was always = 500000, with fix it's >=1.
Can anyone comment as to whether the above fix is correct? It looks right to me, but it would be good if someone familiar with #primitiveNextPut and the AtCache could review it.
The fix is correct. c.f. the body of WriteStream>>nextPut:.
I note that this primitive has not changed since 1998, so this would
rate as a really excellent bug catch!
http://bugs.squeak.org/view.php?id=7421
Thanks, Dave
On Fri, Nov 27, 2009 at 11:38:59AM -0800, Eliot Miranda wrote:
On Fri, Nov 27, 2009 at 9:03 AM, David T. Lewis lewis@mail.msen.com wrote:
On Thu, Nov 26, 2009 at 03:10:52PM +0100, Henrik Johansen wrote:
Interpreter >> primitiveNextPut: limit := self fetchInteger: StreamReadLimitIndex ofObject: stream. atIx := (array bitAnd: AtCacheMask) + AtPutBase. (index < limit and: [(atCache at: atIx+AtCacheOop) = array])
so basically, it needs ReadLimit to be > 0. (Which is only true for
(Read)WriteStreams if created with on:from:to:).
Changing the first line to limit := self fetchInteger: StreamWriteLimitIndex ofObject: stream.
and the primitive now works. ws := WriteStream on: (String new: 500000). [1 to: 500000 do: [:ix | ws nextPut: $a]] timeToRun
before: 130 after: 33
Inserted a counter after the prim call, for the loop above it was always = 500000, with fix it's >=1.
Can anyone comment as to whether the above fix is correct? It looks right to me, but it would be good if someone familiar with #primitiveNextPut and the AtCache could review it.
The fix is correct. c.f. the body of WriteStream>>nextPut:.
Thanks Eliot. The fix is now in VMMaker-dtl.153 on SqueakSource.
Congratulations to Henrik Johansen for finding a bug of rare vintage. This bug has gone undetected in the VM since 12/14/1998. Thanks Henry!
Dave
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Levente Uzonyi